The invention relates to an adjustable abutment arrangement for limiting the stroke of piston and cylinder actuators.
Piston and cylinder actuators are widely used for many different practical purposes. They have a housing made up of a cylinder tube and the two end caps to shut off the two ends of the tube. Within the tube of the actuator there is a piston making sealing contact with its wall so that it may be displaced axially by the action of fluid under pressure. The piston is connected with a piston rod extending through at least one of the end caps. Normally the piston rod constitutes the power output connection of the piston and cylinder actuator. However the piston rod may also be thought of as a stationary rail on which the housing moves axially; in such a case the housing may be connected with the load for the output of power from the actuator. Piston and cylinder actuators are linear motors whose power output connection moves through a certain linear stroke when the actuator is operated.
It is furthermore usual to limit the stroke by means of an abutment arrangement.
Furthermore piston and cylinder actuators have been designed with detectors, as for example in the form of limit switches, to indicate when the power output means of the actuator has reached a certain position. Such detectors may for example form part of a control circuit by which the supply of fluid under pressure to the piston and cylinder actuator is reversed.
A shortcoming with prior art arrangements is that the signal is generated by the detector independently of the abutment function. There is frequently a desire to produce a signal at exactly that point in time when the detector is touched. Conventional components which only have the function of a fixed abutment or of a signal detector, are inherently not in a position to undertake this function and elaborate adjustment is called for in order to ensure even an approximate synchronism between the impact on the abutment and the generation of a signal which may be further processed for control functions.